#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = a; i<=b ; i++)
#define FORD(i, a, b) for (int i = a; i>=b; i--)
#define REP(i, a) for (int i = 0; i<a; i++)
#define N 200100
#define pp pair<int, int>
#define IO cin.tie(NULL);cout.tie(NULL);
#define bit(S, i) ((S >> i) & 1)
template<typename T> inline void read(T &x) {
char c;
bool neg = false;
while (!isdigit(c = getchar()) && c != '-');
x = 0;
if (c == '-') {
neg = true;
c = getchar();
}
do {
x = x * 10 + c - '0';
} while (isdigit(c = getchar()));
if (neg) x = -x;
}
template<typename T> inline void write(T x) {
if (x < 0) {
putchar('-');
write(-x);return;
}
if (x < 10) {
putchar(char(x + 48));
}
else {
write(x/10);
putchar(char(48 + x%10));
}
}
template<typename T> inline void writeln(T x) {
write(x);
putchar('\n');
}
using namespace std;
int n;
vector<pp> e[N];
long long dp[N][4];
void dfs(int u, int p) {
REP(i, 3) dp[u][i] = -1e18;
dp[u][0] = 0;
for (pp tt : e[u]) if (tt.first != p) {
int v = tt.first;
int c = tt.second;
dfs(v, u);
//Prepare
long long t0 = dp[v][0];
long long t1 = dp[v][1] + c;
long long t2 = dp[v][2];
long long add = max(t0, max(t1, t2));
//
FORD(i, 2, 0) {
dp[u][i] += add;
if (i == 1) dp[u][i] = max(dp[u][i], dp[u][i - 1] + max(t0, t2) + c);
if (i == 2) dp[u][i] = max(dp[u][i], dp[u][i - 1] + t0 + c);
}
}
}
int main() {
IO;
// freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
int u, v, c;
read(n);
FOR(i, 2, n) {
read(u);read(v);read(c);
e[u].push_back(pp(v, c));
e[v].push_back(pp(u, c));
}
dfs(1, -1);
writeln(max(dp[1][0], dp[1][2]));
}
